Purifying ferrous metals



Patented Sept. 5, 1933 e I v than? PURIFYING FERROUS METALS Charles T.Hennig, Cleveland, Ohio N Drawing. Original application August 16,

Serial No. 386,490. Divided and this appiication August 12, 1931. SerialNo. 556,613

3 Claims.

This invention relates to the manufacture of steel by the acid or basicBessemer process, and, as to the basic open hearth process, thisapplication is a division of my prior application Serial No. 386,490,filed August 16, 1929, for Patent No. 1,826,881, October 13, 1931.

It is one of the objects of the invention to produce a steel which willhave an exceptionally good surface and also be uniform and withoutinclulO sions or hard spots. I have found that hard spots in steel areusually manganese and iron silicates and oxides and that the eliminationof these segregations of manganese and iron silicates and oxides resultsin the steel having clean surfaces and being more ductile and betteradapted for forging and deep-drawing and for the manufacture of wire andother products. In the Bessemer process, it is common practice, in steelplants, to utilize the hot iron from the blast furnace and the presentinvention relates to the treatment of the metal in the transfer ladle onthe way to the Bessemer converter so as to eliminate, to a large extent,the inclusions and dissolved oxides and silicates prior to the blow. Thetreatment consists preferably in the addition to the metal in the ladleof a purifier which consists essentially of commercial soda ash incombination with certain other materials to control and regulate theaction of the soda ash so as to obtain substantially uniform anddependable results.

In my Patent No. 1,826,881, I have described and claimed a method ofpurifying the metal, which consists in treating it in the ladle, afterthe blow, with said purifier, but it frequently happens that the metalas it comes from the blast furnace, cupola or mixer is not in propercondition because of an excessive amount of oxides and other impuritieswhich will not be eliminated by the blow because the latter is, itself,a process of oxidation. It is, therefore, one of the objects of thisinvention to eliminate these oxides and impurities prior to the blow sothat the metal, after the blow, will contain only the normal amount ofoxides that are formed as a result of the blow.

The purifier may vary as to its composition, but I have found that thefollowing composition is entirely satisfactory:

Commercial soda ash (NazCOa) Calcium oxide (CaO) as limestone Manganesedioxide (M1102) Chlorine, as calcium chloride (CaClz) or sodium chloride(NaCl) 80% to 90% 2% to 6% to 1% The balance of the material consists ofa binder in the form of silica, magnesia, iron and alumina. Thematerials, substantially in the proportions specified, are made up inthe form of briquettes and the binder that is used in these briquettesis preferably glucose or molasses refuse, which is mixed with the othermaterials of the briquettes in a heated condition, the mixture beingthen run through a machine in which it is pressed into briquette form.These briquettes are preferably of a size that would weigh about threeounces each. Instead of making briquettes as described, the materials(without the binder) may be melted at a temperature over 2000 F. andthen run out onto iron plates and broken up into pieces of from inch to3 or 4 inches in size. It is also possible, in making the briquettes, tomix the materials with a small amount of Water which will, through itsaction on the soda ash, produce heat and harden the mixture when it ispressed into briquettes.

The purifier, made into lump form by any of the methods above described,is put into the transfer ladle in which the hot iron is transferred fromthe blastfurnace or mixer to the open hearth or Bessemer converter, andthis may be done either before or during the pouring of the metal intothe transfer ladle.

The action of the purifier results in a violent boiling of the metal,the soda ash being broken up and the carbon dioxide and other gases thatare released causing this and also causing the purifier to be difiusedthroughout the metal. The soda ash takes the oxygen from the dissolvediron oxides and the manganese oxide and also reacts with the ironmanganese silicates forming sodium silicate and metallic iron andmanganese. The sodium silicate rises to the surface of the metal andenters the slag therein. When the action of the purifier has been com- Ipleted, the metal is thoroughly degasified and cleansed of the oxide andother impurities which it originally contained. The resultant slagcontaining the impurities is liquid and very quiet and acts as aprotector for the surface of the 9 metal.

The amount of the purifier to be used will vary from one-half pound tofour or more pounds per ton of metal treated, depending upon theconditions and appearance of the metal, it being understood that thoseskilled in the art are able to determine the condition of the metal fromits appearance and hence, will be able to prescribe the amount ofpurifier that .is to be used in any case.

After the metal has been treated in the transfer ladle, as abovedescribed, it may be poured into the converter and the procedure setforth in my Patent No. 1,826,881 may be followed to remove oxides formedduring the blow.

If the metal is poured into a converter, to make Bessemer steel, theprocedure set forth in my application Serial No. 386,490 may befollowed.

Having thus described my invention, I claim:

1. The hereindescribed method of purifying steel in the course of itsmanufacture by the Bessemer process which consists in treating themolten cast iron while in the transfer ladle and prior to itsintroduction into the Bessemer converter with a deoxidizing material inthe form of an intimate mixture comprising commercial soda ash andmanganese dioxide, and wherein the soda ash is over three-fourths of themixture and the manganese dioxide is an effective amount up to five percent, for controlling the action of the soda ash as and for the purposedescribed.

2. The hereindescribed method of purifying steel in the course of itsmanufacture by the Bessemer process which consists in treating themolten cast iron while in the transfer ladle and prior to itsintroduction into the Bessemer converter with a deoxidizing material inthe form of an intimate mixture comprising commercial soda ash, acalcium compound and manganese dioxide and wherein the soda ash is overthreefourths of the mixture, the calcium compound has a calcium oxidecontent that is an effective amount up to ten per cent, to substantiallyraise the melting point of the soda ash, and the manganese dioxide is aneffective amount, up to five per cent, for controlling the action of thesoda ash as and for the purpose described.

3. The hereindescribed method of purifying steel in the course of itsmanufacture by the Bessemer process which consists in treating themolten cast iron while in the transfer ladle and prior to verter withlumps of a deoxidizing material in its introduction into the Bessemercon- V the form of an intimate mixture comprising com mercial soda ash,a calcium compound and manganese dioxide and wherein the soda ash isover three-fourths of the mixture, the calcium compound has a calciumoxide content that is an effective amount up to ten per cent, tosubstantially raise the melting point of the soda ash, and the manganesedioxide is an effective amount up to five per cent, for controlling theaction of the J soda ash as and for the purpose described.

CHARLES T. HENNIG.

